The question asked me to find the head of a vector [a,b,c] whose length is 3 and is in the same direction as vector(adsbygoogle = window.adsbygoogle || []).push({});

a=[-3,-4,12]

So I found the follwing:

Let vectorxbe the unknown vector

|a|=13

|x|=3

Since they are both in the same direction, they both must have the same direction angles right?

So:

Cos alpha = -3/13 which is equal to a/3

Cos beta = -4/13 which is equal to b/3

Cos gamma = 12/13 which is equal to c/3

Then I got the values for a,b and c but the book shows me a different answer. What am I doing wrong here?

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# Homework Help: Head of a vector

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